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1
Kwok, Philip Chi Lip. "Electrostatics of aerosols for inhalation". Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/1934.
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Electrostatics of aerosols for inhalation is a relatively new research area. Charge properties of these particles are largely unknown but electrostatic forces have been proposed to potentially influence lung deposition. Investigation on the relationship between formulation and aerosol charging is required to understand the fundamental mechanisms. A modified electrical low pressure impactor was employed to measure the particles generated from metered dose inhalers and dry powder inhalers. This equipment provides detailed size and charge information of the aerosols. The particles were sized by impaction onto thirteen stages. The net charges in twelve of the size fractions were detected and recorded by sensitive electrometers. The drug deposits were quantified by chemical assay. The aerosol charge profiles of commercial metered dose inhalers were product-dependent, which was due to differences in the drug, formulation, and valve stem material. The calculated number of elementary charges per drug particle of size ≤ 6.06 μm ranged from zero to several ten thousands. The high charge levels on particles may have a potential effect on the deposition of the aerosol particles in the lung when inhaled. New plastic spacers marketed for use with metered dose inhalers were found to possess high surface charges on the internal walls, which was successfully removed by detergent-coating. Detergent-coated spacer had higher drug output than the new ones due to the reduced electrostatic particle deposition inside the spacer. Particles delivered from spacers carried lower inherent charges than those directly from metered dose inhalers. Those with higher charges might be susceptible to electrostatic forces inside the spacers and were thus retained. The electrostatic low pressure impactor was further modified to disperse two commercial Tubuhaler® products at 60 L/min. The DPIs showed drug-specific responses to particle charging at different RHs. The difference in hygroscopicity of the drugs may play a major role. A dual mechanistic charging model was proposed to explain the charging behaviours. The charge levels on drug particles delivered from these inhalers were sufficiently high to potentially affect deposition in the airways when inhaled. Drug-free metered dose inhalers containing HFA-134a and 227 produced highly variable charge profiles but on average the puffs were negatively charged, which was thought to be due to the electronegative fluorine atoms in the HFA molecules. The charges of both HFAs shifted towards neutrality or positive polarity with increasing water content. The spiked water might have increased the electrical conductivity and/or decreased the electronegativity of the bulk propellant solution. The number of elementary charges per droplet decreased with decreasing droplet size. This trend was probably due to the redistribution of charges amongst small droplets following electrostatic fission of a bigger droplet when the Raleigh limit was reached.
2
Kwok, Philip Chi Lip. "Electrostatics of aerosols for inhalation". Faculty of Pharmacy, 2007. http://hdl.handle.net/2123/1934.
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PhDElectrostatics of aerosols for inhalation is a relatively new research area. Charge properties of these particles are largely unknown but electrostatic forces have been proposed to potentially influence lung deposition. Investigation on the relationship between formulation and aerosol charging is required to understand the fundamental mechanisms. A modified electrical low pressure impactor was employed to measure the particles generated from metered dose inhalers and dry powder inhalers. This equipment provides detailed size and charge information of the aerosols. The particles were sized by impaction onto thirteen stages. The net charges in twelve of the size fractions were detected and recorded by sensitive electrometers. The drug deposits were quantified by chemical assay. The aerosol charge profiles of commercial metered dose inhalers were product-dependent, which was due to differences in the drug, formulation, and valve stem material. The calculated number of elementary charges per drug particle of size ≤ 6.06 μm ranged from zero to several ten thousands. The high charge levels on particles may have a potential effect on the deposition of the aerosol particles in the lung when inhaled. New plastic spacers marketed for use with metered dose inhalers were found to possess high surface charges on the internal walls, which was successfully removed by detergent-coating. Detergent-coated spacer had higher drug output than the new ones due to the reduced electrostatic particle deposition inside the spacer. Particles delivered from spacers carried lower inherent charges than those directly from metered dose inhalers. Those with higher charges might be susceptible to electrostatic forces inside the spacers and were thus retained. The electrostatic low pressure impactor was further modified to disperse two commercial Tubuhaler® products at 60 L/min. The DPIs showed drug-specific responses to particle charging at different RHs. The difference in hygroscopicity of the drugs may play a major role. A dual mechanistic charging model was proposed to explain the charging behaviours. The charge levels on drug particles delivered from these inhalers were sufficiently high to potentially affect deposition in the airways when inhaled. Drug-free metered dose inhalers containing HFA-134a and 227 produced highly variable charge profiles but on average the puffs were negatively charged, which was thought to be due to the electronegative fluorine atoms in the HFA molecules. The charges of both HFAs shifted towards neutrality or positive polarity with increasing water content. The spiked water might have increased the electrical conductivity and/or decreased the electronegativity of the bulk propellant solution. The number of elementary charges per droplet decreased with decreasing droplet size. This trend was probably due to the redistribution of charges amongst small droplets following electrostatic fission of a bigger droplet when the Raleigh limit was reached.
3
Gallavardin, Stéphane. "Analysis concepts of aerosols by on-line aerosol mass spectrometry". [S.l.] : [s.n.], 2006. http://mediatum2.ub.tum.de/doc/603768/document.pdf.
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Alfarra, Mohammedrami. "Insights into atmospheric organic aerosols using an aerosol mass spectrometer". Thesis, University of Manchester, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577471.
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Ma, Yilin. "Developments and improvements to the particle-into-liquid-sampler (PILS) and its applications to Asian outflow studies". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-06072004-131244/unrestricted/ma%5Fyilin%5F200405%5Fphd.pdf.
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Li, Xihao. "Characterization of Perphenazine and Scopolamine Aerosols Generated Using the Capillary Aerosol Generator". VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd/901.
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The characterization of perphenazine and scopolamine aerosols generated using the capillary aerosol generator (CAG) was reported. Variables including steady state power, the formulation vehicle, the drug concentration and the formulation flow rate were studied for their effects on the chemical stability and particle size of these drug aerosols.Stability-indicating HPLC and LC-MS assays were developed and validated for perphenazine and scopolamine, respectively. The chemical stability of each compound was investigated under a variety of stress conditions and the structure of degradation products was proposed.Perphenazine aerosols were generated from propylene glycol (PG) formulations with concentrations of 9, 48 and 90mM at formulation flow rates of 2.5 and 5.0µL/s at a series of steady state powers. At higher aerosolization powers, the low concentration formulation (9mM) degraded with dehalogenation being the major pathway. The size of perphenazine aerosols was between 0.4 to 0.6µm. Changing the solute concentration produced only small changes (~0.2µm) in perphenazine aerosol particle size. The formulation flow rate did not significantly affect the aerosol size.Scopolamine degraded significantly when aerosolized in PG formulations. It was possible to generate chemically stable scopolamine aerosols from ethanol formulations. Significant amounts of degradation products were formed only at or above 4.6W at 5.0µL/s. Hydrolysis and dehydration appeared to be the major degradation pathways at higher powers and low formulation flow rate. The MMAD of scopolamine aerosols was between 0.5 and 2.0µm from 8, 20 and 40mM formulations at 5.0 and 10.0µL/s. The size of scopolamine aerosols increased as a function of increasing the solute concentration. Increasing the formulation flow rate increased the linear velocity of the spray, thus the Reynolds number was increased and smaller particles were generated.
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Wurl, Daniela. "Optimal Estimation Retrieval of Aerosol Microphysical Properties in the Lower Stratosphere from SAGE II Satellite Observations". Thesis, University of Canterbury. Physics and Astronomy, 2007. http://hdl.handle.net/10092/1533.
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A new retrieval algorithm has been developed based on the Optimal Estimation (OE) approach, which retrieves lognormal aerosol size distribution parameters from multiwavelength aerosol extinction data, as measured by the Stratospheric Aerosol and Gas Experiment (SAGE) II in the lower stratosphere. Retrieving these aerosol properties becomes increasingly more difficult under aerosol background conditions, when tiny particles (« 0.1 µm) prevail, to which the experiment is nearly or entirely insensitive. A successful retrieval algorithm must then be able (a) to fill the 'blind spot' with suitable information about the practically invisible particles, and (b) to identify 'the best' of many possible solutions. The OE approach differs from other previously used aerosol retrieval techniques by taking a statistical approach to the multiple solution problem, in which the entire range of possible solutions are considered (including the smallest particles) and characterized by probability density functions. The three main parts of this thesis are (1) the development of the new OE retrieval algorithm, (2) the validation of this algorithm on the basis of synthetic extinction data, and (3) application of the new algorithm to SAGE II measurements of stratospheric background aerosol. The validation results indicate that the new method is able to retrieve the particle size of typical background aerosols reasonably well, and that the retrieved uncertainties are a good estimate of the true errors. The derived surface area densities (A), and volume densities (V ) tend to be closer to the correct solutions than the directly retrieved number density (N), median radius (R), and lognormal distribution width (S). Aerosol properties as retrieved from SAGE II measurements (recorded in 1999) are observed to be close to correlative in situ data. In many cases the OE and in situ data agree within the (OE and/or the in situ ) uncertainties. The retrieved error estimates are of the order of 69% (σN), 33% (σR), 14% (σS), 23% (σA), 12% (σV), and 13% (σReff ). The OE number densities are generally larger, and the OE median particle sizes are generally smaller than those N and R retrieved by Bingen et al. (2004a), who suggest that their results underestimate (N) or overestimate (R) correlative in situ data due to the 'small particle problem'. The OE surface area estimates are generally closer to correlative in situ profiles (courtesy of T. Deshler, University of Wyoming), and larger than Principal Component Analysis (PCA) retrieval solutions of A (courtesy of L. W. Thomason, NASA LaRC) that have been observed to underestimate correlative in situ data by 40-50%. These observations suggest that the new OE retrieval algorithm is a successful approach to the aerosol retrieval problem, which is able to add to the current knowledge by improving current estimates of aerosol properties in the lower stratosphere under low aerosol loading conditions.
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Wan, Chun Hong. "Sugars and polyol compounds in ambient aerosols and cooking fume aerosols /". View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202006%20WAN.
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Svane, Maria. "Aerosol chemistry on the single particle level : an experimental study /". Göteborg : Göteborg University, Department of Chemistry, Atmospheric Science, 2005. http://www.loc.gov/catdir/toc/fy0801/2006411316.html.
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Posselt, Julia Rebekka. "Influence of giant sea salt aerosols on global precipitation and aerosol indirect effect /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17467.
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Dreyfus, Matthew A. "Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 166 p, 2008. http://proquest.umi.com/pqdweb?did=1654492141&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Adikesavalu, Ravichandran. "Preliminary modeling of in-duct desulfurization using condensation aerosols". Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177616476.
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Meyer, Nicholas Karl. "Water uptake of aerosols with a focus on seeded aerosols and instrumentation techniques". Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/26361/1/Nicholas_Meyer_Thesis.pdf.
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This thesis focuses on the volatile and hygroscopic properties of mixed aerosol species. In particular, the influence organic species of varying solubility have upon seed aerosols. Aerosol studies were conducted at the Paul Scherrer Institut Laboratory for Atmospheric Chemistry (PSI-LAC, Villigen, Switzerland) and at the Queensland University of Technology International Laboratory for Air Quality and Health (QUT-ILAQH, Brisbane, Australia). The primary measurement tool employed in this program was the Volatilisation and Hygroscopicity Tandem Differential Mobility Analyser (VHTDMA - Johnson et al. 2004). This system was initially developed at QUT within the ILAQH and was completely re-developed as part of this project (see Section 1.4 for a description of this process). The new VHTDMA was deployed to the PSI-LAC where an analysis of the volatile and hygroscopic properties of ammonium sulphate seeds coated with organic species formed from the photo-oxidation of á-pinene was conducted. This investigation was driven by a desire to understand the influence of atmospherically prevalent organics upon water uptake by material with cloud forming capabilities. Of particular note from this campaign were observed influences of partially soluble organic coatings upon inorganic ammonium sulphate seeds above and below their deliquescence relative humidity (DRH). Above the DRH of the seed increasing the volume fraction of the organic component was shown to reduce the water uptake of the mixed particle. Below the DRH the organic was shown to activate the water uptake of the seed. This was the first time this effect had been observed for á-pinene derived SOA. In contrast with the simulated aerosols generated at the PSI-LAC a case study of the volatile and hygroscopic properties of diesel emissions was undertaken. During this stage of the project ternary nucleation was shown, for the first time, to be one of the processes involved in formation of diesel particulate matter. Furthermore, these particles were shown to be coated with a volatile hydrophobic material which prevented the water uptake of the highly hygroscopic material below. This result was a first and indicated that previous studies into the hygroscopicity of diesel emission had erroneously reported the particles to be hydrophobic. Both of these results contradict the previously upheld Zdanovksii-Stokes-Robinson (ZSR) additive rule for water uptake by mixed species. This is an important contribution as it adds to the weight of evidence that limits the validity of this rule.
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Meyer, Nicholas Karl. "Water uptake of aerosols with a focus on seeded aerosols and instrumentation techniques". Queensland University of Technology, 2008. http://eprints.qut.edu.au/26361/.
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This thesis focuses on the volatile and hygroscopic properties of mixed aerosol species. In particular, the influence organic species of varying solubility have upon seed aerosols. Aerosol studies were conducted at the Paul Scherrer Institut Laboratory for Atmospheric Chemistry (PSI-LAC, Villigen, Switzerland) and at the Queensland University of Technology International Laboratory for Air Quality and Health (QUT-ILAQH, Brisbane, Australia). The primary measurement tool employed in this program was the Volatilisation and Hygroscopicity Tandem Differential Mobility Analyser (VHTDMA - Johnson et al. 2004). This system was initially developed at QUT within the ILAQH and was completely re-developed as part of this project (see Section 1.4 for a description of this process). The new VHTDMA was deployed to the PSI-LAC where an analysis of the volatile and hygroscopic properties of ammonium sulphate seeds coated with organic species formed from the photo-oxidation of á-pinene was conducted. This investigation was driven by a desire to understand the influence of atmospherically prevalent organics upon water uptake by material with cloud forming capabilities. Of particular note from this campaign were observed influences of partially soluble organic coatings upon inorganic ammonium sulphate seeds above and below their deliquescence relative humidity (DRH). Above the DRH of the seed increasing the volume fraction of the organic component was shown to reduce the water uptake of the mixed particle. Below the DRH the organic was shown to activate the water uptake of the seed. This was the first time this effect had been observed for á-pinene derived SOA. In contrast with the simulated aerosols generated at the PSI-LAC a case study of the volatile and hygroscopic properties of diesel emissions was undertaken. During this stage of the project ternary nucleation was shown, for the first time, to be one of the processes involved in formation of diesel particulate matter. Furthermore, these particles were shown to be coated with a volatile hydrophobic material which prevented the water uptake of the highly hygroscopic material below. This result was a first and indicated that previous studies into the hygroscopicity of diesel emission had erroneously reported the particles to be hydrophobic. Both of these results contradict the previously upheld Zdanovksii-Stokes-Robinson (ZSR) additive rule for water uptake by mixed species. This is an important contribution as it adds to the weight of evidence that limits the validity of this rule.
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Zhang, Xiaolu. "The sources, formation and properties of soluble organic aerosols: results from ambient measurements in the southeastern united states and the los angeles basin". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44894.
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900 archived FRM filters from 15 sites over the southeast during 2007 were analyzed for PM2.5 chemical composition and physical properties. Secondary components (i.e. sulfate aerosol and SOA) were the major contributors to the PM2.5 mass over the southeast, whereas the contribution from biomass burning varied with season and was negligible (2%) during summer. Excluding biomass burning influence, FRM WSOC was spatially homogeneous throughout the region, similar to sulfate, yet WSOC was moderately enhanced in locations of greater predicted isoprene emissions in summer. On smaller spatial scale, a substantial urban/rural gradient of WSOC was found through comparisons of online WSOC measurements at one urban/rural pair (Atlanta/Yorkville) in August 2008, indicating important contribution from anthropogenic emissions.
A comparative study between Atlanta and LA reveals a number of contrasting features between two cities. WSOC gas-particle partitioning, investigated through the fraction of total WSOC in the particle phase, Fp, exhibited differing relationships with ambient RH and organic aerosols. In Atlanta, both particle water and organic aerosol (OA) can serve as an absorbing phase. In contrast, in LA the aerosol water was not an important absorbing phase, instead, Fp was correlated with OA mass. Fresh LA WSOC had a consistent brown color and a bulk absorption per soluble carbon mass at 365 nm that was 4 to 6 times higher than freshly-formed Atlanta soluble organic carbon. Interpreting soluble brown carbon as a property of freshly-formed anthropogenic SOA, the difference in absorption per carbon mass between the two cities suggests most WSOC formed within Atlanta is not from an anthropogenic process similar to LA.
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Yeung, Ming Chee. "Study of phase transition and hygroscopic properties of pure and multi-component atmospheric particles by optical microscopic imaging and micro-raman spectroscopy /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202009%20YEUNG.
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Summers, Michael David. "Optical micromanipulation of aerosols". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/779.
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Lavelle, S. P. "Characterisation of bioactive aerosols". Thesis, London South Bank University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618633.
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Lovrić, Josip. "Molecular modeling of aerosols". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10080/document.
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Cette thèse est une étude, au niveau moléculaire, par des méthodes de simulation numérique, des propriétés des aérosols organiques, notamment des aérosols marins, et de leur interaction avec des espèces présentes dans l’atmosphère. L’organisation de la matière organique au sein de ces aérosols joue un rôle fondamental pour leurs propriétés optiques, chimiques et leur rôle comme noyau de condensation pour les nuages.Dans une première partie, on présente contexte atmosphérique et les méthodes de dynamique moléculaire classique et les méthodes mixtes quantique/classique utilisées pour simuler ces aérosols. Ensuite, on décrit l’application de ces méthodes à trois cas.Tout d’abord, on a étudié, par dynamique moléculaire classique (logiciel Gromacs), l’organisation, notamment l’orientation, de molécules d’acide palmitique absorbées sur une surface de sel (NaCl) en fonction du taux de couverture en acide gras et de la température. On présente aussi une étude détaillée de l’influence de l’humidité sur l’organisation de ce film organique à la surface du sel, mettant en évidence l’existence d’îlots d’acide gras monocouches structurés. Dans une seconde étude, la réactivité de NO2 avec cet aérosol marin est traitée par une approche mixte quantique/classique (logiciel CP2K), avec prise en compte de l’impact de l’humidité sur cette réactivité.Enfin, la dernière étude concerne une étude par dynamique moléculaire de phases condensées organiques (n-butanol) et de leur interaction avec des molécules d’eau. Cette étude théorique, complémentaire d’expériences de jets moléculaires, a pour but de mieux comprendre le rôle fondamental que jouent ces interactions pour les propriétés des aérosols et des nuagesIn this thesis numerical methods are used to study the properties, described at the molecular level, of organic aerosols, especially marine aerosols, and their interaction with species in the atmosphere. The organisation of the organic matter in these aerosols plays a key role for their optical, chemical properties, and their ability to act as a cloud condensation nuclei.The first part reviews atmospheric context and the methods (classical molecular dynamics and hybrid quantum/classical approaches) used in this thesis. Then applications to three cases are detailed.Firstly, the organization, more particularly the orientation, of palmitic acid molecules adsorbed on a salt (NaCl) surface as a function of the fatty acid coverage and temperature has been studied using classical molecular dynamics (Gromacs package). The impact of the humidity on the structuration of this organic coating has been described in details, showing the existence of structured fatty acid island-like monolayers on NaCl surface.In a second study, the reactivity of NO2 with these heterogeneous marine aerosols has been investigated by a hybrid quantum/classical method (CP2K package), with taking into account the effect of the humidity.The last study is a classical molecular dynamics of n-butanol crystal, water accommodation at these surfaces and simulation of water jet collision with n-butanol surface. These simulations, complementary to experiments, were performed to better understand the fundamental role of the water-organic matter interaction on the properties of the aerosols and clouds
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Sukhapan, Jariya. "Surfactants in atmospheric aerosols". Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251504.
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Tripathi, Sachchida Nand. "Removal of charged aerosols". Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325074.
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Davidson, Nicholas Mark. "Atmospheric processing of aerosols". Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8298/.
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The chemistry of aerosol particles is critical to the influence said particles have over human health, air quality and the distribution of nutrients across the world. Current models estimate that windborne dust represents the movement of thousands of teragrams of solid material of varying composition and solubility across continents and into the world’s oceans. Understanding the composition and surface reactivity of anthropogenic particles from industry, agriculture and vehicle emissions is vital to understanding their potential impact on the world, and the structure and behaviour of inhalable pharmaceuticals is a strong determinant of their efficacy. The following work examines a broad selection of natural and anthropogenic particulate samples with synchrotron-based techniques, including analysis of ship emissions collected directly from stacks for the first time. The effect of simulated atmospheric acid processing on the solubility of iron on coal fly ash is evaluated, and optical trapping is used in conjunction with analytical techniques to observe the influence of relative humidity on the properties of pharmaceutical aerosols and aqueous droplets containing fluorescent protein solutions.
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ROVELLI, GRAZIA. "Characterizing the hygroscopic properties of aerosols: from binary aqueous systems to atmospheric aerosols". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/104639.
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The quantification of the hygroscopic properties of atmospheric aerosols is important to understand several processes they are involved in, such as clouds formation, their interaction with solar radiation and the penetration of particles in the human respiratory track. In addition, the interaction of deposited aerosols with surfaces depends on their physical state, too; thus, characterizing their phase transitions as a function of their chemical composition is key to understanding the effects they have on materials (e.g. printed circuits, cultural heritage artifacts).
In order to investigate the hygroscopic properties of aerosols, an electrical conductance method in an Aerosol Exposure Chamber was developed for the determination of the phase transitions of PM2.5 aerosol samples during relative humidity cycles. The obtained Deliquescence and Crystallization Relative Humidity (DRH and CRH) were put in relation with the ionic chemical composition of the analyzed samples: it was found that seasonal chemical variations result in seasonal trends for DRH and CRH, too. The implications of these results for Free-Cooled Data Centers, for the understanding of the role of particles in stone-decay processes of cultural heritage artifacts and for the common algorithms used in the remote sensing of particulate matter concentrations were evaluated.
The ionic fraction characterisation was also used as an input for a state-of-the-art equilibrium aerosol model (E-AIM) to simulate the DRH of the samples. Some discrepancies were evidenced in the comparison of experimental and modelled values, because the hygroscopic properties of the organic components need to be included too. In order to effectively account for their contribute, current aerosol models need to be refined with accurate hygroscopicity measurements on organic compounds of increasing molecular complexity and their mixtures with common electrolytes. Such measurements are essential for understanding and modelling the microphysical properties that determine the partitioning of water between the gas and the aerosol phases in chemically complex systems.
In this context, an experimental technique based on evaporation kinetics measurements in an Cylindrical Electrodynamic Balance was developed for the measurement of hygroscopic properties on single confined droplets from aqueous solutions with known chemical composition. To expand the range of applicability of a previously developed technique to water activities from 0.5 to values close to saturation (>0.99), well-characterized binary and ternary inorganic mixtures were considered. The obtained results were used to successfully validate this technique by comparing them with calculations from E-AIM model and to assess the sensitivity of this technique to small changes in chemical composition. The first class of atmospherically relevant compounds that was considered was aminium sulphates, which are the products of the neutralization reactions of sulphuric acid and short-chained alkylamines (methyl- and ethylamines). They have been detected in atmospheric aerosols up to hundreds of pg m-3, but their hygroscopic behaviour was less characterized than their inorganic equivalent, ammonium sulphate, even if they can promote cloud droplets formation and particle growth.
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Sodeman, David Alan. "Characterization of ambient, automobile, and diesel aerosols utilizing aerosol time of flight mass spectrometry /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3144344.
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Mills, Jessica Breyan. "Evaluation of the DiSCmini personal aerosol monitor for submicrometer sodium chloride and metal aerosols". Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2584.
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This work evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride, NaCl, and spark generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <103; Medium, 103-104; and High, >104 particles/cm3). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared to those measured with reference instruments, a scanning mobility particle sizer (SMPS) and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 16% of those measured by the CPC for polydispersed aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +101% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm but caution should be exercised when particles larger than 300 nm are present.
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Zuluaga-Arias, Manuel D. "Spatio-temporal variability of aerosols in the tropics relationship with atmospheric and oceanic environments". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41202.
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Earth's radiation budget is directly influenced by aerosols through the absorption of solar radiation and subsequent heating of the atmosphere. Aerosols modulate the hydrological cycle indirectly by modifying cloud properties, precipitation and ocean heat storage. In addition, polluting aerosols impose health risks in local, regional and global scales.
In spite of recent advances in the study of aerosols variability, uncertainty in their spatial and temporal distributions still presents a challenge in the understanding of climate variability. For example, aerosol loading varies not only from year to year but also on higher frequency intraseasonal time scales producing strong variability on local and regional scales. An assessment of the impact of aerosol variability requires long period measurements of aerosols at both regional and global scales.
The present dissertation compiles a large database of remotely sensed aerosol loading in order to analyze its spatio-temporal variability, and how this load interacts with different variables that characterize the dynamic and thermodynamic states of the environment. Aerosol Index (AI) and Aerosol Optical Depth (AOD) were used as measures of the atmospheric aerosol load. In addition, atmospheric and oceanic satellite observations, and reanalysis datasets is used in the analysis to investigate aerosol-environment interactions. A diagnostic study is conducted to produce global and regional aerosol satellite climatologies, and to analyze and compare the validity of aerosol retrievals. We find similarities and differences between the aerosol distributions over various regions of the globe when comparing the different satellite retrievals. A nonparametric approach is also used to examine the spatial distribution of the recent trends in aerosol concentration. A significant positive trend was found over the Middle East, Arabian Sea and South Asian regions strongly influenced by increases in dust events.
Spectral and composite analyses of surface temperature, atmospheric wind, geopotential height, outgoing longwave radiation, water vapor and precipitation together with the climatology of aerosols provide insight on how the variables interact. Different modes of variability, especially in intraseasonal time scales appear as strong modulators of the aerosol distribution. In particular, we investigate how two modes of variability related to the westward propagating synoptic African Easterly Waves of the Tropical Atlantic Ocean affect the horizontal and vertical structure of the environment. The statistical significance of these two modes is tested with the use of two different spectral techniques. The pattern of propagation of aerosol load shows good correspondence with the progression of the atmospheric and oceanic synoptic conditions suitable for dust mobilization over the Atlantic Ocean. We present extensions to previous studies related with dust variability over the Atlantic region by evaluating the performance of the long period satellite aerosol retrievals in determining modes of aerosol variability. Results of the covariability between aerosols-environment motivate the use of statistical regression models to test the significance of the forecasting skill of daily AOD time series. The regression models are calibrated using atmospheric variables as predictors from the reanalysis variables. The results show poor forecasting skill with significant error growing after the 3rd day of the prediction. It is hypothesized that the simplicity of linear models results in an inability to provide a useful forecast.
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Capes, Gerard. "Aging of biomass burning aerosols and formation of secondary organic aerosols over West Africa". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498784.
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Atmospheric aerosols represent an important but uncertain component of the atmosphere, which are known to affect the Earth's radiative budget by scattering and absorbing solar and terrestrial radiation, and by influencing the optical properties and lifetime of clouds. Organic aerosols are a ubiquitous feature of atmospheric composition around the globe, yet also represent a significant source uncertainty with regard to the understanding of aerosol behaviour and their representation m regional and global models. Presented here are aircraft measurements of organic aerosols arising from biomass burning and biogenic production over West Africa; the predominant sources of submicron aerosols during the dry and wet seasons in a region which has received comparatively little study in the literature. Measurements were taken usuig an Aerodyne Quadrupole Aerosol Mass Spectrometer (Q-AMS) installed on the UK Facility for Atmospheric Measurements (FAAM) aircraft. The physical and chemical properties of biomass burning aerosols were investigated on a continental scale, with particular focus on the evolution of these characteristics as the aerosols aged during transport from the source region. Systematic evolution of the chemical composition of aerosols was observed and aerosols became increasingly oxygenated with increasing distance from source. Emission ratios were estimated for black carbon and organic carbon, which compare well with previous results though the estimates made here are on regional scales rather than from single fires. Evolution of the particle size distribution was dominated by coagulation rather than condensation, and negligible secondary organic aerosol (SOA) production was observed. The chemical evolution of biomass burning aerosols without an increase in mass from secondary production appears to be a consistent finding for biomass burning aerosols, when the same analysis was completed for biomass burning emissions from other regions.
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Laucks, Mary Lisa. "Quantifying the uncertainties in measurements of aerosol optical properties relevant to the direct shortwave forcing of climate /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10314.
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Pierce, Flint G. "Aggregation in colloids and aerosols". Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/348.
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Knox, Christopher James Henry. "The photochemistry of liquid aerosols". Thesis, University of Canterbury. Chemistry, 2002. http://hdl.handle.net/10092/6076.
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The photochemistry of liquid aerosols has been investigated with the aim of using the physical properties of liquid aerosols to enhance the reactivity of photochemical and
photocatalytic systems.
The properties of aerosols that enhance reactivity are summarised under four headings: the optics of micro droplets, diffusion into small particles, surface and interfacial reactivity, and capillarity effects.
A range of systems have been developed for the photochemistry of liquid aerosols. A number of photocatalytic systems have been studied and a significant enhancement in the photolysis of molybdenum hexacarbonyl has been observed, relative to the liquid phase.
A computational study of the light intensity distribution inside liquid aerosols droplets in photochemical and photocatalytic systems has been carried out. Large enhancements of the internal field intensity relative to the incident field have been observed. It is proposed that the internal intensity distributions are the source of the increased rate of molybdenum
hexacarbonyl photolysis.
A model has been proposed for gas-liquid transfer, based on the capillary wave motion of the liquid surface.
31
Simo, John A. (John Alfred). "Turbulent transport of inertial aerosols". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/38716.
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Tranchant, Benoît. "Simulations numeriques des aerosols marins". Nantes, 1997. http://www.theses.fr/1997NANT2009.
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Les aerosols marins jouent un role essentiel dans de nombreux processus dynamiques et thermodynamiques dans la couche de surface atmospherique marine. Ils affectent notamment la propagation electro-optique et influencent aussi de nombreux processus meteorologiques. L'objectif de cette etude est l'elaboration et le developpement d'outils numeriques permettant de caracteriser les interactions des flux turbulents d'embruns generes a la surface de la mer avec les flux turbulents de chaleurs dans la couche de surface atmospherique marine. Le code numerique seacluse se decompose en deux parties. La premiere partie comprend un modele de vagues, adapte a la pleine mer ou aux mers cotieres, au-dessus desquelles le champ 2-d de vent moyen est calcule. La partie principale du code est un modele eulerien qui calcule les distributions des concentrations d'embruns (10 r 250 m), de vapeur d'eau et de temperature, du creux des vagues au sommet de la couche de surface. L'evaporation partielle des embruns est simulee a l'aide de transferts de masse d'eau liquide entre categories d'embruns, et de vapeur d'eau et de chaleur entre celles-ci et l'air. Les equations de convection-diffusion d'embruns sont discretisees en volumes finis, le schema de diffusion est centre et le schema de convection est hybride. La resolution est effectuee a l'aide de l'algorithme t. D. M. A. Ligne par ligne. Les simulations ont demontre que la dynamique des aerosols est largement influencee par le mouvement moyen induit par les vagues et que le transport turbulent est efficace pour les plus petits aerosols (r 60 m) mais peu pour les plus gros embruns. Les comparaisons avec les donnees experimentales sont encourageantes pour des vents moderes a forts qui impliquent une production importante d'embruns a la surface. L'evaporation des embruns semble peu modifier les spectres d'embruns. En revanche, l'influence des embruns sur les flux de chaleurs sensible et latente semble importante par vents forts
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Warren, Dale Ross Seinfeld John H. "Nucleation and growth of aerosols /". Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03212008-085926.
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Wexler, Anthony S. Seinfeld John H. Seinfeld John H. "Inorganic components of atmospheric aerosols /". Diss., Pasadena, Calif. : California Institute of Technology, 1991. http://resolver.caltech.edu/CaltechETD:etd-07172007-083859.
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Silva, Leticia Caetano da [UNESP]. "Propriedades químicas e físicas do material particulado atmosférico e seus efeitos no crescimento de partículas". Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/108489.
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000747315.pdf: 2387128 bytes, checksum: 66912d8d58c3818da96b0516f50c2314 (MD5)Aerossóis são espécies sólidas ou líquidas suspendidas e/ou transportadas pelo ar, com diâmetro médio da ordem nano ou micrométrica. Os aerossóis podem modificar a atmosfera do planeta, afetar a saúde dos seres vivos, alterar a visibilidade e até mesmo o clima e a disponibilidade de água potável. Estes fatos justificam a necessidade de melhorar o conhecimento sobre suas características físicas e químicas. As rápidas mudanças na quantidade e composição dos aerossóis na atmosfera são resultados de atividades antrópicas que estão se intensificando como resultado de expansão econômica. Fora dos centros urbanos, as atividades relacionadas ao agronegócio são responsáveis por grande parte da emissão dos aerossóis. A região do centro-oeste paulista destaca-se pela grande área destinada à plantação de cana-de-açúcar. Parte significativa ainda utiliza a queima da palha para facilitação da colheita manual. O presente estudo descreve a caracterização química e física do material particulado atmosférico no interior do estado de São Paulo no período entre Maio de 2010 a Fevereiro de 2012. O maior número de amostras foi coletada na região central do estado, no município de Araraquara, dentro do Campus da Unesp, localizado a sudoeste da área urbana. Outras amostras foram coletadas a sudoeste do Estado, no município de Ourinhos, no Campus da UNESP, localizado a 5 km do centro urbano Nesta campanha participaram diferentes grupos de pesquisa. Para a coleta do aerossol utilizou-se filtros de Teflon e vazão de amostragem de ≈9 L min-1. Este procedimento possibilitou a coleta do material particulado suspenso total. Nas amostras coletadas foram determinadas as espécies iônicas solúveis em água por cromatografia de íons (NH4+, Na+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, PO43-, C2O42-. O equipamento utilizado não permitiu a separação das espécies orgânicas acetato e formiato, apresentadas aqui como a somatórias...
Aerosols are suspended solid or liquid species and / or airborne, with an average diameter of the nano or micron order. Aerosols can modify the atmosphere of the planet, affect the health of living beings, change the visibility and even the weather and availability of drinking water. These facts justify the need to improve the knowledge about their physical and chemical characteristics. Rapid changes in the amount and composition of aerosols in the atmosphere are the result of human activities, which are increasing as a result of economic expansion. Outside urban centers , the activities related to agribusiness are responsible for much of the emission of aerosols. The region of the center - west of São Paulo is distinguished by large area for sugar cane crop. Significant part still uses the of straw burning to facilitate the manual harvesting. The present study describes the chemical and physical characterization of atmospheric particulate matter in the state of São Paulo in the period from May 2010 to February 2012. The largest number of samples was collected in the central region of the state, the city of Araraquara, UNESP at the Campus, located southwest of the urban area. Other samples were collected southwest of the state , in the Ourinhos city, at the campus of UNESP, located 5 km from the city center. Together the campaign participated different research groups. To collect the aerosol was used Teflon filters and flow sampling ≈ 9 L min-1. This procedure allowed the collection of total suspended particulate matter. In the collected samples were determined water soluble ionic species by ion chromatography (NH4+, Na+, K+ , Mg2+ , Ca2+ , Cl- , NO3- , SO42- , PO43- , C2O42-). Equipment used did not enabled the separation of organic species acetate and formate, shown here as the summation of these organic anions ( H3CCOO- + HCOO-). In parallel directly measurements were performed to get the number concentration of particles...
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Souza, Michele de Lima. "Estudo da distribuição de tamanhos e composição iônica de aerossóis e seus efeitos na capacidade de nuclear gotas de nuvens /". Araraquara, 2016. http://hdl.handle.net/11449/136462.
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Orientador: Arnaldo Alves CardosoBanca: Paulo Clairmont Feitosa de Lima Gomes
Banca: Theotonio Mendes Pauliquevis Júnior
Banca: Adalgiza Fornaro
Banca: Bernardino Ribeiro de Figueiredo
Resumo: Este trabalho buscou evidências para reconhecer mudanças sazonais nas emissões e consequentes mudanças na composição de aerossóis presentes em uma região subtropical a fetada pela queima de biomassa agrícola. Aquisições de dados de distribuição de tamanho e amostragem de aerossol foram feitas próximas ao centro geográfico do estado de São Paulo, no município de Araraquara. A composição iônica das espécies solúveis foram determinadas pela técnica da cromatografia de íons. Diferentes concentrações numéricas da fração mais fina de aerossóis mostraram ser dependentes de condições atmosféricas e, portanto, mostram variações sazonais na formação e crescimento de partículas. A o corrência preferencial de processos de nucleação homogênea, foram mais pronunciados durante os meses mais chuvosos de verão. Já os processos de nucleação heterogênea, foram favorecidos durante o inverno, quando ocorrem emissões mais intensas da queima de b iomassa. A moda de nucleação e a moda de Aitken foram favorecidas no período úmido (verão) e períodos de seca (inverno queima de biomassa), respectivamente. A moda de acumulação mostrou picos no verão e no inverno, o que pode ser explicado pelo crescimento das partículas por efeitos de higroscopicidade e reações heterogêneas concomitantes. Também buscou - se quantificar o possível efeito da presença de aerossóis localizados próximos ao solo nas propriedades das nuvens. Para buscar evidências de interção aeros sol - nuvem foram coletados dados a respeito do raio efetivo da gota e da profundidade óptica da nuvem. Estes dados foram obtidos pelo tratamento das medidas realizadas por satélites que orbitam sobre a região de estudo. Os resultados obtidos ao longo de ma is de um ano indicaram que as fontes de emissões regionais contribuem para a emissão de aerossóis primários ou formação de aerossóis secundários, que...
Abstract: This study aimed to recognize seasonal changes in emissions and consequent changes in the composition of aerosols present in a subtropical region affected by the agricultural biomass burning. Data acquisition relat ed to the size distribution and aerosol samples were taken near the geog raphical center of the São Paulo state, in the city of Araraquara. The ionic composition of the soluble species were determined by the ion - chromatography technique. Different numerical concentrations of the finer fraction of aerosols showed to be dependent of the atmospheric conditions and, thus, show ed seasonal variations in particle formation and growth. The preferential occurrence of homogeneous nucleation processes were more pronou nced during the rainy summer months. But, the heterogeneous nucleation processes were favored during the winter, when there are more intense emissions from biomass burning. The nucleation and Aitken modes were favored in the wet season (summer) and dry per iods (winter biomass burning), respectively. Accumulation mode showed peaks in summer and winter, which can be explained by the growth of the particles by the effects of hygroscopicity and concur rent heterogeneous reactions. This work also sought to quanti fy the possible effect of the presence of aerosols located close to the ground in the clouds properties.To seek evidence of aerosol - cloud interaction, data were collected about the effective radius of the drop and the optical depth of the cloud. These data were obtained from satellites that orbiting over the region of study. The results of the studies over more than one year indicated that the sources of regional emissions contribute to the emission of primary aerosols or formation of secondary aerosols, that can influence the cloud formation process. These facts suggest that the seasonal human activities in the region can alter the composition of the aerosol and this, in t...
Doutor
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Silva, Leticia Caetano da. "Propriedades químicas e físicas do material particulado atmosférico e seus efeitos no crescimento de partículas /". Araraquara, 2013. http://hdl.handle.net/11449/108489.
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Orientador: Arnaldo Alves CardosoBanca: Mercedes de Moraes
Banca: Janaína Braga do Carmo
Banca: Lilian Rothschild Franco de Carvalho
Banca: Gisele Olimpio da Rocha
Resumo: Aerossóis são espécies sólidas ou líquidas suspendidas e/ou transportadas pelo ar, com diâmetro médio da ordem nano ou micrométrica. Os aerossóis podem modificar a atmosfera do planeta, afetar a saúde dos seres vivos, alterar a visibilidade e até mesmo o clima e a disponibilidade de água potável. Estes fatos justificam a necessidade de melhorar o conhecimento sobre suas características físicas e químicas. As rápidas mudanças na quantidade e composição dos aerossóis na atmosfera são resultados de atividades antrópicas que estão se intensificando como resultado de expansão econômica. Fora dos centros urbanos, as atividades relacionadas ao agronegócio são responsáveis por grande parte da emissão dos aerossóis. A região do centro-oeste paulista destaca-se pela grande área destinada à plantação de cana-de-açúcar. Parte significativa ainda utiliza a queima da palha para facilitação da colheita manual. O presente estudo descreve a caracterização química e física do material particulado atmosférico no interior do estado de São Paulo no período entre Maio de 2010 a Fevereiro de 2012. O maior número de amostras foi coletada na região central do estado, no município de Araraquara, dentro do Campus da Unesp, localizado a sudoeste da área urbana. Outras amostras foram coletadas a sudoeste do Estado, no município de Ourinhos, no Campus da UNESP, localizado a 5 km do centro urbano Nesta campanha participaram diferentes grupos de pesquisa. Para a coleta do aerossol utilizou-se filtros de Teflon e vazão de amostragem de ≈9 L min-1. Este procedimento possibilitou a coleta do material particulado suspenso total. Nas amostras coletadas foram determinadas as espécies iônicas solúveis em água por cromatografia de íons (NH4+, Na+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, PO43-, C2O42-. O equipamento utilizado não permitiu a separação das espécies orgânicas acetato e formiato, apresentadas aqui como a somatórias...
Abstract: Aerosols are suspended solid or liquid species and / or airborne, with an average diameter of the nano or micron order. Aerosols can modify the atmosphere of the planet, affect the health of living beings, change the visibility and even the weather and availability of drinking water. These facts justify the need to improve the knowledge about their physical and chemical characteristics. Rapid changes in the amount and composition of aerosols in the atmosphere are the result of human activities, which are increasing as a result of economic expansion. Outside urban centers , the activities related to agribusiness are responsible for much of the emission of aerosols. The region of the center - west of São Paulo is distinguished by large area for sugar cane crop. Significant part still uses the of straw burning to facilitate the manual harvesting. The present study describes the chemical and physical characterization of atmospheric particulate matter in the state of São Paulo in the period from May 2010 to February 2012. The largest number of samples was collected in the central region of the state, the city of Araraquara, UNESP at the Campus, located southwest of the urban area. Other samples were collected southwest of the state , in the Ourinhos city, at the campus of UNESP, located 5 km from the city center. Together the campaign participated different research groups. To collect the aerosol was used Teflon filters and flow sampling ≈ 9 L min-1. This procedure allowed the collection of total suspended particulate matter. In the collected samples were determined water soluble ionic species by ion chromatography (NH4+, Na+, K+ , Mg2+ , Ca2+ , Cl- , NO3- , SO42- , PO43- , C2O42-). Equipment used did not enabled the separation of organic species acetate and formate, shown here as the summation of these organic anions ( H3CCOO- + HCOO-). In parallel directly measurements were performed to get the number concentration of particles...
Doutor
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Sullivan, Amy Patricia. "The Ambient Organic Aerosol Soluble in Water: Measurements, Chemical Characterization, and an Investigation of Sources". Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-05022006-111928/.
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Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2007.Rodney J. Weber, Committee Chair ; Michael H. Bergin, Committee Member ; Committee Member ; Martial Taillefert, Committee Member ; Paul H. Wine, Committee Member.
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Hsieh, Wei-Chun. "Representing droplet size distribution and cloud processes in aerosol-cloud-climate interaction studies". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29619.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009.Committee Chair: Athanasios Nenes; Committee Member: Andrew G. Stack; Committee Member: Irina N. Sokolik; Committee Member: Judith A. Curry; Committee Member: Mike Bergin; Committee Member: Rodney J. Weber. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Steele, Henry Donnan 1974. "Investigations of cloud altering effects of atmospheric aerosols using a new mixed Eulerian-Lagrangian aerosol model". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/58445.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2004.Includes bibliographical references (p. 275-315).
Industry, urban development, and other anthropogenic influences have substantially altered the composition and size-distribution of atmospheric aerosol particles over the last century. This, in turn, has altered cloud albedo, lifetime, and patterns which together are thought to exert a negative radiative forcing on the climate; these are the indirect effects of atmospheric aerosols. The specifics of the process by which aerosol particles seed cloud particles are complex and highly uncertain. The goal of this thesis is to refine understanding of the role of various aerosol types in determining cloud properties. We approach this goal by constructing a new highly detailed aerosol-cloud process model that is designed to simulate condensation upon complex aerosol populations. We use this model to investigate the microphysics of aerosol-cloud interactions, specifically considering the role of cloud dynamics and of the ubiquitous mixed soot / sulfate aerosols. We describe the Mixed Eulerian-Lagrangian Aerosol Model (MELAM). This new computer model of aerosol microphysics is specifically tailored to simulate condensation and activation as accurately as possible. It specifically calculates aerosol thermodynamics, condensation, coagulation, gas and aqueous phase chemistry, and dissolution. The model is able to consider inorganic aerosols and aerosols with both inorganics and insoluble cores; the specific chemical system to be considered is specified by the user in text input files. Aerosol particles may be represented using "sectional distributions" or using a "representative sample" distribution which tracks individual particles.
(cont.) We also develop a constant updraft speed, adiabatic parcel model and a variable updraft speed, episodically entraining parcel model to provide boundary conditions to MELAM and allow simulations of aerosol activation in cloud updrafts. Using MELAM and the parcel models, we demonstrate that aerosol activation depends on the composition and size distribution of the sub-cloud aerosol population, on the updraft speed through a parcel's lifting condensation level, on the vertical profile of the updraft speed, and on entrainment. We use a convective parameterization that was developed for use in global or regional models to drive the episodically entraining, variable updraft speed parcel model. Ultimately, reducing the uncertainty of the global impact of the indirect effects of aerosols will depend on successfully linking cloud parameterizations to models of aerosol activation; our work represents a step in that direction. We also consider the activation of mixed soot / sulfate particles in cloud updrafts. We constrain for the first time a model of condensation onto these mixed particles that incorporates the contact angle of the soot / solution interface and the size of the soot core. We find that as soot ages and its contact angle with water decreases, mixed soot / sulfate aerosols activate more readily than the equivalent sulfate aerosols that do not have soot inclusions. We use data from the Aerosol Characterization Experiments (ACE) 1 and 2, and from the Indian Ocean Experiment (INDOEX) to define representative aerosol distributions for clean, polluted, and very polluted marine environments. Using these distributions, we argue that the trace levels of soot observed in clean marine environments do not substantially impact aerosol activation, while the presence of soot significantly increases the number of aerosol that activate in polluted areas.
by Henry Donnan Steele.
Ph.D.
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Aiken, Allison Carol. "Quantitative chemical analysis of ambient organic aerosols using high-resolution time-of-flight aerosol mass spectrometry". Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337069.
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Peltier, Richard Edward. "Ambient Submicron Particles In North America: Their Sources, Fate, and Impact". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19750.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008.Committee Chair: Weber, Rodney J.; Committee Member: Bergin, Michael H.; Committee Member: Huey, L Gregory; Committee Member: Ingall, Ellery D.; Committee Member: Nenes, Athanasios.
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Vinchurkar, Samir C. "Numerical Analysis of Respiratory Aerosol Deposition: Effects of Exhalation, Airway Constriction and Electrostatic Charge". VCU Scholars Compass, 2008. http://hdl.handle.net/10156/2014.
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Thesis (Ph. D.)--Virginia Commonwealth University, 2008.Prepared for: Dept. of Mechanical Engineering. Includes bibliographical references (leaves 212-233). Also available online via the Internet.
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Indoitu, Rodica. "Chemical properties of aerosols over Israel /". [Sede Boker] : Albert Katz International School for Desert Studies, 2006. http://aranne5.lib.ad.bgu.ac.il/others/IndoituRodica.pdf.
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Engvall, Ann-Christine. "Properties and origin of arctic aerosols /". Stockholm : Department of Meteorology, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7524.
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Megner, Linda. "Meteoric Aerosols in the Middle Atmosphere". Doctoral thesis, Stockholm : Department of Meteorology, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7734.
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Rowland, Glenn Anthony. "The photochemistry of sulfuric acid aerosols". Thesis, University of Canterbury. Chemistry, 2001. http://hdl.handle.net/10092/5949.
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We report here the experimental investigation of several photochemical reactions that may occur in concentrated sulfuric acid droplets in the clouds of the planet Venus.
It was found that the irradiation of 80-100wt.% sulfuric acid aerosol with 193nm light in the presence of carbon monoxide resulted in the formation of carbon dioxide and either the formation or destruction of sulfur dioxide. The measured quantum yield for carbon dioxide formation is 0.011±0.010.
Various instrumental techniques for determining the size and number density of aerosol droplets were utilised in an attempt to generate a stable, monodisperse sulphuric acid aerosol.
Concentrated sulfuric acid solutions were irradiated with 178.3nm, 184.9nm, 193.3nm and 253.7nm light in order to investigate the UV photochemistry of the bulk liquid. No significant photochemistry was observed. The reactions occurring in sulfuric acid aerosol at 193nm were attributed to multiphoton processes, permitted by the optical focussing effects observed in small droplets.
Irradiation of solutions of Fe(II) in 98wt.% sulfuric acid solution with 193nm or 248nm light results in the formation of Fe(III). Under the same conditions, the reduction of Fe(III) is also observed. The presence of sulfur dioxide increases the initial rate of the reaction, and dissolved oxygen is consumed in the initial stages.
A qualitative mechanism for the photochemical interconversion of Fe(II) and Fe(III) in concentrated sulfuric acid is proposed, which incorporates the effect of sulfur dioxide and oxygen on the reaction.
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Hamilton, Douglas Stephen. "Effects of natural aerosols on climate". Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16272/.
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Natural aerosols are a key component of many biogeochemical cycles, they define the baseline from which the pre‒industrial to present‒day anthropogenic aerosol radiative forcing is calculated, and they dominate the net effect of all aerosols on the incoming solar radiation. However, their impacts on climate are complex, often nonlinear, and poorly understood; leading to large uncertainties. Global model simulations are used in this thesis to define aerosol regions unperturbed by anthropogenic pollution. On a global annual mean, unperturbed aerosol regions cover 12% of the Earth (16% of the ocean surface and 2% of the land surface) with about 90% of unperturbed regions occurring in the Southern Hemisphere. In cloudy regions with a radiative forcing relative to 1750, results suggest that unperturbed aerosol conditions could still occur on a small number of days per month. However, these environments are mostly in the Southern Hemisphere, potentially limiting the usefulness in reducing Northern Hemisphere forcing uncertainty. Clustering techniques were used to identify natural emissions regimes in the pre-industrial and present-day where biomass burning, biogenic volatile organic compounds, dimethyl sulphide, volcanic sulphur dioxide and sea spray emissions dominate the variance in cloud condensation nuclei concentrations. Regimes are generally located in regions close to each emission source, before significant mixing occurs within the atmosphere with other emission types. These regimes are ideal “natural laboratory” locations for field study of the impacts of each natural emission on aerosol behaviour. When pre-industrial fire emissions from two global fire models are implemented in a global aerosol model, pre-industrial global mean cloud condensation nuclei concentrations increase by a factor 1.6-2.7 relative to the widely used AeroCom dataset. Higher pre-industrial aerosol concentrations cause a substantial reduction in the calculated global mean cloud albedo forcing of between 40 and 88 percent and a reduction in the direct radiative forcing of between 5 and 10 percent. When compared to twenty-eight other sources of uncertainty in our model, pre-industrial fire emissions are by far the single largest source of uncertainty in pre-industrial cloud condensation nuclei concentrations, and hence in our understanding of the magnitude of the historical radiative forcing due to anthropogenic aerosol emissions.
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Chatain, Audrey. "Aerosols-plasma interaction in Titan’s ionosphere". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASV022.
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Le système climatique de la lune de Saturne Titan est gouverné par la production intense d’aérosols organiques dans sa haute atmosphère. Ce phénomène s’est aussi certainement produit sur Terre au moment de l’apparition de la vie. Ces deux points motivent fortement les recherches sur les processus de formation et d’évolution des aérosols dans l’atmosphère de Titan. Les aérosols se forment et restent plusieurs semaines dans l’ionosphère, étendue d’environ 900 à 1200 km d’altitude. Cette région de l’atmosphère est ionisée par le rayonnement solaire UV et des particules énergétiques provenant de la magnétosphère de Saturne. Des espèces plasma très réactives sont ainsi présentes : des radicaux, des espèces excitées, des ions et des électrons. Dans un tel environnement, je me suis intéressée à l’interaction entre les aérosols organiques et le plasma.Ce phénomène est simulé en laboratoire avec une expérience développée à cet effet : des analogues des aérosols de Titan sont exposés à une décharge plasma en N2-H2. J’observe qu’à la fois les grains et la phase gaz évoluent. Les atomes H et N interagissent chimiquement avec les aérosols. Puis, du cyanure d’hydrogène (HCN) ainsi que d’autres molécules organiques sont éjectées en phase gaz par le bombardement ionique. Ces résultats mettent en évidence une contribution importante des processus hétérogènes dans l’ionosphère de Titan.Ma ré-analyse des données de la sonde de Langmuir de la mission Cassini a d’autre part révélé la présence d’une population d’électrons inattendue dans l’ionosphère, sous 1200 km d’altitude et côté jour, zone dans laquelle des ions lourds ont également été détectés. Ces électrons pourraient être émis par les aérosols, après collision avec un photon et/ou après chauffage par la chimie ionique très active dans cette régionThe climatic system of Saturn’s moon Titan is governed by the intense production of organic aerosols in its upper atmosphere. This phenomenon also certainly happened on Earth at the beginning of life. These two points strongly motivate research on the formation and evolution processes of the aerosols in the atmosphere of Titan. The aerosols form and stay several weeks in the ionosphere, between ~900-1200 km of altitude. This atmospheric layer is ionized by UV solar rays and energetic particles coming from Saturn’s magnetosphere, forming a plasma with very reactive species: radicals, excited species, ions and electrons. In such an environment, the main question I tackle is how the organic aerosols interact with the plasma species.The phenomenon is simulated in the laboratory with a plasma setup developed on purpose: analogues of Titan aerosols are exposed to a N2-H2 plasma discharge. Both an evolution of the solid and the gas phase are observed. H and N atoms chemically interact with the aerosols. Then, hydrogen cyanide (HCN) and other organic molecules are ejected in the gas phase by ion sputtering. These results highlight an important contribution of heterogeneous processes in Titan’s upper atmosphere.My re-analysis of the Cassini Langmuir probe data revealed the presence of an unexpected electron population in the ionosphere, below 1200 km and on the day-side, where heavy ions are also detected. These electrons could be emitted by the aerosols, after collision with a photon, and/or heating by the active ion chemistry
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Riggs, Charles Alan. "Adsorption isotherms of cesium reactor aerosols /". free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074439.
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